John Cleves Symmes (1779-1829), an American supporter of the Hollow Earth theory, went on an expedition to the North Pole to prove that the earth was hollow. He claimed in his book, Symmes Theory of Concentric Spheres (1878), that there were open holes at the north and south poles. Symmes’s theory of concentric spheres, polar voids, and open poles argued against Newton’s theory of gravity. Symmes argued that hollow spheres exert pressure on objects. Also, Symmes believed that the crust of the earth was a thousand miles thick. Thus, the magnetized north on a compass only confused sailors trying to navigate Antarctica or the Artic circles. Symmes also reasoned that the Magellanic Clouds were actually reflections of Tasmania and New Zealand, seen through the southern opening of the South Pole.